Pneumatic valve bodies often have bores with internal grooves in which O-rings are inserted. Movement of pneumatic valve stems in the bores of the valve bodies causes wear and damage to the O-rings which must be replaced periodically. Various types of devices have been proposed for replacing O-rings.
U.S. Pat. No. 4,141,129 to Martini describes an O-ring insertion tool with a barrel and a mandrel that forms an opening through which an O-ring is ejected. The O-ring is inserted at a depth that depends on the length of the mandrel. An operator of this tool cannot see the position of the O-ring while the tool is used. It has been found that insertion of an O-ring at an angle described by this patent causes the O-ring to twist and jam inside the valve bore.
U.S. Pat. No. 3,639,972 to Schelin et al. involves a valve structure with a sleeve that slides in a bore. O-rings are seated in grooves in the exterior of the sleeve which is placed inside a tube. The tube, containing the sleeve, is inserted into the bore and then removed. However, the sleeve remains in the bore, with its external O-rings in place.
U.S. Pat. No. 3,553,817 to Lallak concerns a tool for installing seals, with a grooved mandrel in a sleeve. A seal is placed on the grooved mandrel, and the sleeve is moved over the seal. The tool is then inserted into a bore and the sleeve is withdrawn against substantial resistance of the seal. The seal is only partially released from the mandrel. Thus the seal is easily dislodged from a groove when the mandrel is removed from the bore. This tool prevents the operator from determining when the seal is adjacent a particular groove within a bore.
U.S. Pat. No. 3,455,011 to Harding describes a pliers type of tool for inserting O-rings into recesses of bores. This tool has a pin jaw that deforms an O-ring against a horseshoe jaw. The tool is inserted into a bore where the O-ring is installed into a groove of the bore by opening the jaws. However, the jaws are prevented from opening completely by the bore, which keeps the O-ring slightly deformed. Thus, when the tool is removed from the bore, the jaws tend to dislodge the ring from its position in a groove.
U.S. Pat. No. 3,289,286 to Belanger deals with an O-ring seating tool. This tool is used to insert an O-ring into a surface annulus formed by a counterbore. A sleeve rolls the O-ring over a tube extending from the annulus. The sleeve also seats the O-ring in the annulus.
U.S. Pat. No. 3,180,015 to Thompson et al. mentions a tool for inserting O-rings into annular sockets. Two slide members hold an O-ring for insertion into a bore. The slide members are surrounded by a sleeve. The sleeve can be a variety of lengths to insert an O-ring at a desired depth within the bore. A handle moves the slides within the sleeve to hold and release the O-ring. A user of this tool cannot see whether the O-ring is aligned with the socket or is jammed, when attempting to insert the O-ring.
Thus a need exists for a seal insertion apparatus that, during insertion; prevents jamming of the seal in a body bore, allows a view of the seal during insertion; and provides a guide for the seal to a particular annular groove.